Neste trabalho, determinou-se a energia de ativação (Ea) no processo de combustão de três óleos combustíveis cedidos pela Petrobrás–Cenpes e denominados por A, B e C. Empregou-se análise termogravimétrica (TG) utilizando um sistema Shimadzu 51H e, para todas as amostras observaram-se três regiões oxidativas distintas identificadas como, oxidação à baixa temperatura (LTO), depósito de combustível (FD) e oxidação à alta temperatura (HTO). As energias de ativação foram determinadas como uma função do grau de conversão ('alfa') e temperatura na região LTO e utilizando-se dois métodos cinéticos, denominados ASTM E 1641 (Flynn eWall) e Model Free Kinetics de Vyazovkin. Empregaram-se as seguintes razões de aquecimento: 2,5; 5,0; 10,0; 15,0 e 20,0°C por min entre a temperatura ambiente e 600°C. As demais condições experimentais foram: massa da amostra de aproximadamente 20 mg, suporte de amostra de alumínio e gás de arraste ar sintético com vazão de 100 mL/min. Os valores de Ea encontrados foram os mesmos para ambos os métodos cinéticos: 44 ± 7% kJ/mol ('alfa'=0,1 a 0,9) para amostra A. Para a amostra B os valores de Ea foram em média de 48 ± 4% kJ/mol ('alfa'=0,1 a 0,5) e 66 ± 16% kJ/mol ('alfa'=0,5 a 0,9) e, para a amostra C os valores de Ea foram em média de 58 ± 4% kJ/mol ('alfa'=0,1 a 0,5) e 65 ± 5% kJ/mol ('alfa'=0,5 a 0,9). Conclui-se que a Ea pode ser usada como um parâmetro adequado para apontar uma tendência de comportamento e para caracterizar diferentes óleos sob processo de combustão / In this work activation energies (Ea) in the combustion of three fuels oils were determined through thermogravimetry. The oil samples, here named A, B and C were supplied by Petrobras-Cenpes. The thermogravimetric experiments were performed in a Shimadzu TGA-51H analyzer. In all the combustion experiments three distinct oxidation regions were observed, identified as low temperature oxidation (LTO), fuel deposition (FD) and high temperature oxidation (HTO). Activation energies were determined as a function of conversion degree ('alfa') and temperature for LTO region, following two different procedures, namely Model Free Kinetics and ASTM E 1641. Transient experiments were performed from room temperature up to 600°C, at heating rates of 2.5, 5.0, 10.0, 15.0 and 20.0°C for min. Samples of 20.0 ± 0.5 mg and aluminum crucibles were used. The reacting atmosphere was synthetic air, which was continuously blown over the samples, throughout the analyzer furnace, at a volumetric rate of 100 mL/min. The activation energies resulted equal for both considered methods. For oil A, the activation energy resulted 44 ± 7% kJ/mol ('alfa'=0.1 to 0.9). For oil B it resulted in average 48 ± 4% kJ/mol ('alfa'=0.1 to 0.5) and 66 ± 16% kJ/mol ('alfa'=0.5 to 0.9). For oil C the activation energy resulted 58 ± 3% kJ/mol ('alfa'=0.1 to 0.5) e 65 ± 5% kJ/mol ('alfa'=0.5 to 0.9). It is concluded that the oxidation activation energy is a suitable parameter concerning to point out a tendency of behavior and characterizing different oils under combustion process

Growing environmental concerns, such as global warming, are giving rise to new regulations imposed by the International Maritime Organization (IMO) on sulfur content for marine fuels, thus, constraining refining processes. Oxidative desulfurization (ODS) is an appealing desulfurization method with some advantages over traditional processes like hydrodesulfurization (HDS), such as mild operating conditions and no-hydrogen consumption. ODS could be employed as a complementary or alternative process for HDS. During the oxidative desulfurization, the organo-sulfur compounds are oxidized to polar sulfones. Then, such sulfones are separated from the treated fuel oil using techniques such as liquid-liquid extraction. In the present work, the separation of oxidized sulfur-containing compounds of heavy fuel oil using ultrasound-assisted technology has been investigated and simulated in Aspen Plus. The oxidant selected was hydrogen peroxide, while the catalyst was acetic acid. The chosen solvent for the sulfone separation was acetonitrile. The primary goal of this work is to successfully emulate the operation performed by an oxidative desulfurization pilot plant-scale apparatus designed by Tecnoveritas®, which will later allow the analysis of the parameters on the overall sulfur removal efficiency.

In order to increase the efficiency of a preheating system as temperatures increase, without using seawater as a coolant, an additional heat exchanger is required to be installed into the system. The purpose of the study is therefore to investigate how the temperatures of fuel oils can be increased while minimising the loss of energy and costs. The study was conducted in Karlshamn Power Station's (kvt) preheating system on Block 3. The study was conducted via Design for six sigma (DFSS) according to the primary design concept SG2 to guarantee the study's understanding of empirical data, and the development of solutions. The study resulted in two variants of heat exchangers where one is an identical Shell and Tube heat exchanger from Siljan Allards AB and the other one is a Supermax Shell and Plate heat exchanger from Tranter International.

Ship exhausts contain high levels of sulphur oxides, nitrogen oxides, carbon dioxide and particles dueto the heavy fuel oil, HFO, used for combustion and the combustion characteristics of the engine.As a result of upcoming stricter regulations for shipping pollution, as well as growing attentionto greenhouse gas emissions, air pollution and uncertainty of future petroleum oil supply, a shifttowards a cleaner burning fuel is needed.This work explores potential alternative fuels, both conventional and unconventional, and abatementtechnologies, to be used by tankers in the worldwide spot market to comply with upcomingenvironmental regulations in the near and coming future. As a reference the product tanker M/TGotland Marieann is used and recommendations for which fuel that shall be used by the referenceship in 2015 and 2020 are presented.The environmental assessment and evaluation of the fuels are done from a life cycle perspective usingresults from Life Cycle Assessment, LCA, studies.This study illustrates that, of the various alternatives, methanol appears to be the best candidatefor long-term, widespread replacement of petroleum-based fuels within tanker shipping. It does notemit any sulphur oxides nor particles and the nitrogen oxides are shown to be lower than those ofmarine gas oil, MGO. The global warming potential of the natural gas produced methanol is notlower than that of MGO, but when gradually switching to bio-methanol the greenhouse gas emissionsare decreasing and with methanol the vision of a carbon free society can be reached.For 2015 a switch towards methanol is not seen as realistic. Further research and establishment ofregulations and distribution systems are needed, however there are indications that a shift will bepossible sometime between 2015 and 2020. For 2015 a shift towards MGO is suggested as it involveslow investment costs and there is no need for infrastructure changes. As MGO is more expensivethan methanol, a shift is preferable as soon as the market, technology and infrastructure are ready.

Abstract: Global decarbonization requires addressing local challenges and advancing appropriate technologies. In this dissertation, an investigation of appropriate carbon capture technologies for CO2 capture from heavy fuel oil (HFO) fired power plants, common locally, is presented. Two emerging technologies are considered, chemical looping combustion (CLC) and calcium looping (CaL). In a preliminary study, CLC and CaL implementation at an HFO-fired power plant are modeled using Aspen software, and based on the results, CaL is selected for further experimental investigation. Briefly, CaL is a high temperature separation process that utilizes limestone-derived CaO tosimultaneously concentrate CO2 and capture SO2 from flue gas. The solid CaO particles are cycled between carbonation and calcination, CaO + CO2 ⇋ CaCO3, in a dual fluidized bed system and experience capture capacity decay with cycling. Structurally distinct limestones were procured from the two geologic regions where limestone is mined in Saudi Arabia. Using bubbling fluidized bed reactor systems, the capture performance of these two limestones, and a German limestone of known performance, were compared. The combined and individual influence of flue gas H2O and SO2 content, the influence of textural changes caused by sequential calcination/carbonation cycles, and the impact of CaSO4 accumulation on the sorbents’ capture performance were examined. It was discovered that metamorphosed limestone-derived sorbents exhibit atypical capture behavior: flue gas H2O negatively influences CO2 capture performance, while limited sulfation can positively influence CO2 capture. The morphological characteristics influencing sorbent capture behavior were examined using imaging and material characterization tools, and a detailed discussion is presented. Saudi Arabian limestones’ deactivation rates were examined by thermogravimetric analysis. A quantitative correlation describing sulfation deactivation was developed. The validity of amending the conventional semi-empirical sorbent deactivation model with the novel correlation was supported by subsequent pilot scale (20 kWth) experiments. Solving process mass and energy balances, reasonable limits on operating parameters for CaL implementation at HFO-fired power plants were calculated. The influence of power plant configuration, carbonator design, and limestone source on power plant energy efficiency are considered and a discussion is presented. Finally a commentary on the potential of this technology for local implementation and required future work is presented.

Experimental measurement of fuel properties are expensive, require sophisticated instrumentation and are time consuming. Mathematical models and approaches for predicting fuel properties can help reduce time and costs. A new approach for characterizing petroleum fuels called the functional group approach was developed by disassembling the innumerable fuel molecules into a finite number of molecular fragments or ‘functional groups’. This thesis proposes and tests the following hypothesis, Can a fuels functional groups be used to predict its combustion properties? Analytical techniques like NMR spectroscopy that are ideally suited to identify and quantify the various functional groups present in the fuels was used. Branching index (BI), a new parameter that quantifies the degree and quality of branching in a molecule was defined. The proposed hypothesis was tested on three classes of fuels namely gasolines, diesel and heavy fuel oil. Five key functional groups namely paraffinic CH3, paraffinic CH2, paraffinic CH, naphthenic CH-CH2 and aromatic C-CH groups along with BI were used as matching targets to formulate simple surrogates of one or two molecules that reproduce the combustion characteristics. Using this approach, termed as the minimalist functional group (MFG) approach surrogates were formulated for a number of standard gasoline, diesel and jet fuels. The surrogates were experimentally validated using measurements from Ignition quality tester (IQT), Rapid compression machine (RCM) and smoke point (SP) apparatus. The functional group approach was also employed to predict research octane number (RON) and motor octane number (MON) of fuels blended with ethanol using artificial neural networks (ANN). A multiple linear regression (MLR) based model for predicting derived cetane number (DCN) of hydrocarbon fuels was also developed. The functional group approach was also extended to study heavy fuel oil (HFO), a viscous residual fuel that contains heteroatoms like S, N and O. It is used in ships as marine fuel and also in boilers for electricity generation. 1H NMR and 13C NMR measurements were made to analyze the average molecular parameters (AMP) of HFO molecules. The fuel was divided into 19 different functional groups and their concentrations were calculated from the AMP values. A surrogate molecule that represents the average structure of HFO was then formulated and its properties were predicted using QSPR approaches.

Land-based turbine engines are currently used to burn heavy fuel oil (HFO), which is a lower cost fuel. HFO contains inorganic material that forms deposits on turbine blades reducing output and efficiency. Magnesium based additives are used to inhibit vanadium pentoxide deposition and reduce the corrosive nature of the gas and deposits in the hot gas path of the gas turbine. The focus of this study was to determine particle morphology and elemental composition of ash when firing HFO in an atmospheric combustor at various fuel injector atomization pressures. Prior to firing, the HFO was washed with water to remove sodium and potassium. A commercially available magnesium based additive was used to inhibit the vanadium in the HFO. Fuel was injected using an air-blast atomizer at air blast atomization gage pressures of 117, 186, and 255 kPa. Ash was collected from three locations downstream of combustion: immediately following combustion (pre-cyclone), from a cyclone separator (cyclone), and finally from a position located after the cyclone separator (post-cyclone). A Philips XL30 Scanning Electron Microscope (SEM) provided images, weight percent of elements of the ash, and element maps. Images taken from the SEM clearly show two particle types: 1) hollow spherical particles, or cenospheres, and 2) submicron agglomerated spherical particles. The cenospheres contained high carbon concentrations and were found primarily in the cyclone and probe bag filter. Element maps show that cenospheres, regardless of size, predominately contain carbon, oxygen, and sulfur with lesser amounts of sodium, magnesium, aluminum, and silicon. Particles collected downstream of the cyclone were primarily sub-micron in size and inorganic in composition. It is postulated that the cenospheres are the result of incomplete combustion of fuel oil droplets while the submicron spheres are nucleated inorganic material that initially evaporated from the liquid droplets. Particle size analysis was performed for each sample location. As the injection pressure was increased; the pre-cyclone and cyclone locations had similar number mean diameters that would decrease with increasing pressure. The diameter of the post-cyclone location did not change significantly with increasing air atomization. While increasing atomization pressure decreased the carbon content of the ash at all measurement locations, the atomization had little influence on the inorganic composition of the particles. The fine condensed phase particles and the larger cenosphere particles both produced similar compositions of inorganic material.

Baigiamajame magistro darbe nagrinėjama dirbtinės (137Cs) ir gamtinės (40K, 226Ra, 232Th) kilmės radionuklidų ir sunkiųjų metalų (Ni, Cu, Cr, Cd, Pb, Zn) kaupimasis AB „Lietuvos elektrinė“ mazute ir jo degimo proceso atliekose bei šių teršalų sklaida elektrinės įtakos zonoje. Eksperimente naudojamas mazutas, mazuto pelenai, elektrostatinio filtro pelenai, gipsas ir dirvožemis, surinktas elektrinės įtakos zonoje. Visuose bandiniuose gama spektrometrijos būdu išmatuoti radionuklidų savitieji aktyvumai ir atominės absorbcijos būdu išmatuotos sunkiųjų metalų koncentracijos. Gauti rezultatai lyginami skaičiuojant teršalų kiekių santykius tarp mazuto, jo degimo proceso atliekų ir dirvožemio. Vertinami teršalų kiekiai elektrinės atliekų kaupe. Remiantis eksperimentinių tyrimų duomenimis sudarytas radionuklidų ir sunkiųjų metalų sklaidos iš elektrinės kamino modelis. Darbą sudaro septynios dalys: įvadas, tyrimo objekto ir problemos aptarimas, eksperimentinių tyrimų metodika, rezultatų analizė, modeliavimas, bendrosios išvados ir rekomendacijos, literatūros sąrašas. Darbo apimtis – 87 p. be priedų, 19 lentelių, 33 paveikslai. Atskirai pridėti priedai ir moksliniai straipsniai. / In the final thesis is analysed fuel oil burning process waste contamination of artificial (137Cs), naturally occuring (40K, 226Ra, 232Th) radionuclides and heavy metals (Ni, Cu, Cr, Cd, Pb, Zn) at SC „Lietuvos elektrinė“. In the experiment were used samples or fuel oil, fuel oil ash, electrostatic precipitator ash, gypsum and soil. Specific activity of radionuclides was measured using gamma spectrometer and using atomic absorption method were measured concentrations of heavy metals. The results are compared calculating the quantity of pollution between oil, the combustion of waste and soil. Contaminants concentrations valued in power plant’s wastes. Based on experimental data was used power plant stack dispersion model. The thesis consists of seven parts: introduction, discussion of the problem, experimental research methodology, analysis of results, modeling, conclusions, recommendations and list of references. The thesis has 87 pages of text excluding appendixes, 19 tables, 33 figures. Appendixes and scientific articles are added separately.

[pt] Com a probabilidade de ocorrer derrames de óleo em águas marinhas e a carência de informação sobre o comportamento de metais neste evento, viu-se a necessidade de se intensificar estudos referentes aos complexos metálicos, para que se possa entender a competição entre os ligantes do petróleo e os ligantes da água do mar. Para isto é necessário determinar a estabilidade dos complexos formados no petróleo, compará-los com os correspondentes na água do mar. Neste trabalho foram estudados os sistemas binários de complexos de ácido hexanóico (ligante que representa os ácidos carboxílicos do petróleo) e 1-propanotiol (representante das mercaptans) com os íons metálicos de interesse para a indústria do petróleo - Ni(II), V(IV) e Fe(II) - por estarem presentes em maior quantidade. Embora presentes em menor quantidade, Cd(II) e Pb(II) foram estudados por serem metais tóxicos e controlados pelas organizações ambientais. O ácido hexanóico apresenta o oxigênio do grupamento carboxilato, como sítio de coordenação enquanto que o 1-propanotiol possui o enxofre do grupamento tiol. O estudo da complexação foi realizado em solução utilizando a titulação potenciométrica e a espectrofotometria de ultravioleta- visível, Foram calculadas as constantes de dissociação dos ligantes e de formação dos complexos ML, ML2, ML3, MLOH, ML(OH)2, ML(OH)3, ML2OH, ML2(OH)2, ML3OH. Os valores das constantes de estabilidade dos complexos poderiam ser divididos em dois grupos: o dos complexos binários com ácido hexanóico e os complexos binários do 1- propanotiol. Dos complexos formados com o ácido hexanóico, a espécie ML com o íon metálico Pb(II) foi que apresentou maior estabilidade. No sistema onde temse complexos com 1-propanotiol, a espécie ML do íon metálico Cd(II) foi o que apresentou maior estabilidade. Na distribuição de espécies com ligantes representantes do petróleo e ligantes da água do mar observou-se a formação de complexos em pH = 7 para os íon metálicos V(IV), Ni(II) e Fe(II) com o ácido hexanóico. Para o íon metálico Pb(II) o complexo formado foi com o 1- propanotiol. Já para o íon Cd(II) houve a formação de complexo com o cloreto. Para o íon Cd(II), neste pH houve formação de pouca proporção de complexos com 1-propanotiol e um percentual maior (60 por cento) de complexos com os íons cloreto e sulfato da água do mar. Entretanto, como a concentração de cádmio é em torno de ppb no óleo combustível, este valor tem pouca relevância em termos de poluição. Assim, se estes ligantes estudados, que são monodentados, ligam-se preferencialmente aos metais do que os ligantes da água, com certeza isto acontece com os ligantes polidentados do petróleo como por exemplo as porfirinas. Com a utilização da técnica de espectrofotometria de ultravioletavisível foi possível observar as bandas referentes a transferência de carga e banda d-d. Foi realizada também uma simulação de derrame de óleo combustível. Para isto analisou-se a concentração de metais foi medida em tempos variados. Os dados teóricos e da simulação confirmam que íons metálicos ficam retidos no óleo mesmo quando há derrame do óleo na água do mar. / [en] In face of the probability of occurrences of oil spill in marine waters and the lack of information concerning the behavior of the metals in such events, it is necessary to intensify the studies of metal complexes in order to understand the competition between oil ligands and sea water ligands. For such, it is necessary to determine the stability of the complexes formed in oil and compare them with the correspondent ones in sea water. In the present work the binary systems of the complexes of hexanoic acid (a ligand that represents the carboxylic acids of the oil) and 1-propanethiol (which represents the mercaptans) with the metal ions of interest to the petroleum industry - Ni(II), V(IV) and Fe (II) - were studied because they are present in greater quantities. Despite being present in smaller quantities, Cd(II) and Pb(II) were also studied because they are toxic and controlled by environmental organizations. Hexanoic acid has an oxygen atom of the carboxylate group as donor atom, and 1-propanethiol has a sulfur atom of the thiol group. The complexation study was performed in solution using potentiometric titration and ultraviolet-visible spectrophotometry. The dissociation constants of the ligands and the formation constants of the complex species ML, ML2, ML3, MLOH, ML(OH)2, ML(OH)3, ML2OH, ML2 (OH)2 and ML3(OH) were calculated. The values of the stability constants can be divided in two groups: one with the binary complexes of hexanoic acid and the other with the binary complexes of 1-propanethiol. Among the complexes formed with hexanoic acid, the ML species with metal ion Pb(II) was the most stable. In the system of the complexes with 1-propanethiol, the ML species with Cd(II) was the most stable. In the species distribution as a function of pH including the representative ligands of oil and sea water, it could be observed that at pH =7 the most stable species for the metal ions V(IV), Ni(II) and Fe (II) were those with hexanoic acid. In relation to ion Pb(II) the complex formed was with 1- propanethiol. Cd(II), this pH occurred the formation of a small proportion of the complex with 1-propanethiol and a higher percentual (60 percent) of the complexes with the chloride and sulfate íons of sea water. Since the concentration of Cd(II) is in the range of ppb, this metal ion is less relevant when pollution is concerned. Thus, if the monodentate oil ligands studied in this work preferably bind metal ions rather than sea water ligands, than this certainly happens with the polydentate oil ligands such as porphyrins. Using the ultraviolet-visible spectrophotometry technique it was possible to observe the charge transfer bands and the d-d bands. A simulation of oil dispersion was also performed and the concentration of the metals was measured at various times. Both theoretical and simulation data showed that the metal ions are retained in the oil, even when the oil is spread in sea water.

Oil spills, especially in water have happened throughout the years. The consequences from this kind of incident have always been a threat to marine life and take a lot of money and time to clean up. The forensic investigations of oil usually focus on oil spill in water, however, this kind of investigation can be applied on more areas, such as in sexual offense cases and arson. The oil from the crime scene and the oil from the suspected source are analyzed and compared to each other to see if the compositions match. The aim of this thesis was to optimize the clean-up process of heavy fuel oil (HFO) using solid-phase extraction (SPE) according to the European Committee for standardization (CEN) 15522-2 method. HFOs are black oils, containing particles and soot which will decrease injector performance. Thus, a cleanup procedure is attractive when analyzing such samples. The three factors of optimization in this study were elution volumes, solvents, and SPE sorbents.The SPE method used in this study was to use the cartridges as a filter; therefore, the samples were both loaded and eluted with an organic solvent, in this case dichloromethane (DCM) or dichloromethane/heptane (DCM/Hp). The gas chromatography mass spectrometry (GC-MS) analysis method used is described in Annex B in the CEN 15522-2 method.Concluding, increasing the eluent volume did not indicate improvement on the extraction method. In terms of the solvents, both dichloromethane and dichloromethane/heptane showed similar results. The percentage weathering plots (PW-plots) showed that the SPE sorbents (dual layer florisil/Na2SO4, florisil and silica gel sorbents) worked similar. The overall conclusion from this thesis work was that further optimization must be made before implementing the method.